10.4.2.2 Precautionary Considerations
In decision making, the precautionary principle is considered when possibly
dangerous, irreversible, or catastrophic effects are identified, but scientific
evaluation of the potential damage is not sufficiently certain, and actions
to prevent these potential adverse effects need to be justified (Jonas, 1985;
ORiordan and Cameron, 1994; CEC, 2000). The precautionary principle implies
an emphasis on the need to prevent such adverse effects. It thus acknowledges
societal risk preferences, which are, plausibly, that humankind would rather
be risk averse than risk neutral or risk seeking if one considers, for instance,
future climate-induced loss of GNP (Pearce, 1994; Jaeger et al., 1998). Hence,
attitudes towards risk play a key role in decision making under uncertainty.
However, one might also favour prevention to cure even where one is certain
about the damage.
With the precautionary principle, uncertainty about the damage to be incurred
does not serve as an argument to delay action. In the face of great uncertainty,
a precautionary approach might even result in a more stringent emission-reductions
target and/or adaptational response (Cantor and Yohe, 1998).
The evaluation of uncertainty and the necessary precaution is plagued with
complex pitfalls. These include the global scale, long time lags between forcing
and response, the impossibility to test experimentally before the facts arise,
and the low frequency variability with the periods involved being longer than
the length of most records (Moss and Schneider, 2000). Some of these uncertainty
aspects may be irreducible in principle, and hence decision makers will have
to continue to take action under significant uncertainty, so the problem of
climate change evolves as a subject of risk management in which strategies are
formulated as new knowledge arises (Jaeger et al., 1998).
Aspects of uncertainty are associated with each link of the causal chain of
climate change, beginning with GHG emissions, covering damage caused by climate
change, followed by a set of mitigation and adaptation measures (Jepma and Munasinghe,
1998). In particular, damage-function estimates are prone to low confidence
as they involve uncertainty in both natural and socioeconomic systems. To quantify
the impact of climate change on flora and fauna needs consideration of many
effects because of the complexity of the biological and ecological systems.
Similarly, the manner in which humans adapt to climate change is not well known,
socioeconomic modules are still at a stage of low disaggregation, and damage
as a function of vulnerability, adaptation and time-dependency is poorly understood
(Tol et al., 1998; Tol, 1999a, 1999b).
However, following the precautionary principle, uncertainty is not an argument
for delaying action, as the UNFCCC acknowledges in Article 3.3: parties should
take precautionary measures to anticipate, prevent or minimize the causes
of climate change and mitigate its adverse effects. Where there are threats
of serious or irreversible damage, lack of full scientific certainty should
not be used as a reason for postponing such measures... (UNFCCC, 1993).
Pursuing this principle, mitigation and adaptation measures are to be implemented
before full information is available and uncertainties regarding the scope and
timing of climate change are resolved. Yet, the question of timing and extent
of mitigation and/or adaptation policies remains unquantified by the precautionary
principle (Portney, 1998).